Polyvinyl chloride plasticized with dialkoxyalkyl homoterephthalates



United States Patent 3,224,995 POLYVINYL CHLORIDE PLASTlCllZED WITHDIALKOXYALKYL HOMOTEREPHTHALATES David 0. De Pree, Baton Rouge, La.,,assignor to Ethyl Corporation, New York, N.Y., a corporation of 1963,Ser. No. 287,737

4 Claims. (Cl. 260-3L4) This application is a division of applicationSerial No. 89,677 filed February 16, 1961, now abandoned.

This invention relates to novel dialkyl and dialkoxyalkylhomoterephthalates and their addition to various resins and polymers asa plasticizer. This invention in particular relates to plasticcompositions wherein improved properties are produced by theincorporation into the resins mass of a dialkyl homoterephthalate or adialkoxyalkyl homoterephthlate. This invention further relates of theuse of a novel dialkyl and dialkoxyalkyl homoterephthalates as syntheticlubricants.

In' the field of vinyl chloride resins it has been well established thatthe commercial values of such products are to a large degree directlydependent upon the modifying plasticizer used. The amount of thespecific plasticizer used, of course, depends not only on theplasticizer itself but also on the properties required in the finishedproduct, e.g., floor tile, plastic garden hose, shower curtains,raincoats, etc. Regardless of the end use, however, there are certaintechnical properties which a good plasticizer must possess. These arecompatibility, efliciency, permanence, and low temperature flexibility.Over and above these technical properties there are other certaindesirable characteristics which a plasticizer should have, such aspleasant odor and unobjectionable color. Furthermore, the plasticizershould not have the objectionable feature goes toxicity, while at thesame time it should be fairly mildew and fungus resistant. In additionto all of these properties the plasticizer should be inexpensive.

In the last few years new developments in aircraft and guided missilefields have created applications for lubricents and instrument oilswhich cannot be met by the conventional petroleum based lubricants, evenwhen these are improved by the best additives known. New types of turbojet and turbo prop transport aircraft must fly at high altitudes and athigh engine operating temperatures. The lubricants, hydraulic fluids andinstrument oils used in these planes must therefore function attemperatures as low as 100 F. to as high as 350 F. The best availablepetroleum lubricants are too viscous at these low temperatures and aredecomposed at the high temperatures. It has therefore been necessary todevelop for these applications wholly synthetic lubricants which meetthe rigid standards set forth hereinabove.

Accordingly, it is an object of this invention to provide a new class ofplasticizers. It is a further object to provide new compounds whichpossess the numerous properties of good plasticizers. It is still afurther object to provide new compounds which can be used as syntheticlubricants. Another object is to provide plasticized compositions andplasticizing methods, especially those involving polyvinyl chloride.Other objects will become more apparent from the following discussionand appended claims.

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It is now found that these and other objects are accomplished by theprovision of esters of homoterephthalic acid having the formula whereinR is an .alkyl or alkoxyalkyl group having from 4 to about 24 carbonatoms. Preferred compounds of this invention are those in which saidgroups contain from about 6 to about 18 carbon atoms. These compoundsare preferred because of their excellent balance of compatibility,permanence and efiiciency as plasticizers. The most particularlypreferred compounds of this invention are di-n-octyl homoterephthalate,di-Z-ethylhexyl homoterephthalate, and dibutoxyethyl homoterephthalate.These compounds are most particularly preferred because they possess anoptimum ratio of solubilizing groups, i.e., ester groups, to the totalmolecular weight of the respective compounds. Hence these particularcompounds have especially excellent plasticizer properties.

Another embodiment of this invention is the use as synthetic lubricantsof the esters of homoterephthalic acid as described above wherein eachalkyl or alkoxyalkyl group contains from 4 to 18 carbon atoms. The mostpreferred compounds are those in which the alkyl or alkoxyalkyl groupcontains from about 6 to about 12 carbon atoms. The compounds containingthis number of carbon atoms are preferred because of the optimum lowtemperature viscosity properties which they possess. The mostparticularly preferred compounds of this embodiment are di-Z-ethylhexylhomoterephthalate and diehexyl homoterephthalate. These compounds aremost preferred because of their high temperature stability and ideal lowtemperature viscosity characteristics as well as their splendidlubricating ability.

Another embodiment of this invention is polyvinyl chloride and othersimilar resins containing a dialkyl homoterephthalate or a dialkoxyalkylhomoterephthalate as described above in an amount ranging from about 10to about weight percent of the ester suflicient to plasticize thepolyvinyl chloride. Mixtures of dialkyl homoterephthalates anddialkoxyalkyl homoterephthalates may also be used in polyvinyl chlorideand related resins to impart excellent plasticizing properties thereon.

A further embodiment of this invention is the process of plasticizingpolyvinyl chloride and related resins, wherein a dialkylhomoterephthalate or dialkoxyalkyl homoterephthalate, as describedabove, is mixed with polyvinyl chloride. This process may beaccomplished under the application of heat, e.g., at a temperature offrom about 20 C. to about 300 C. The amount of heat used depends on thetype of process used to plasticize the resin, i.e., dry blend or rollmill and the like. The amount of the ester used in this process rangesfrom about 10 to about 80 weight percent of the polyvinyl chloride used.

Typical examples of the compounds of this invention are di-n-butylhomoterephthalate, diisobutyl homoterephthalate, di-n-heriylhomoterephthalate, diisohexyl homoterephthalate, di-Z-methylhexylhomoterephthalate, di-B-ethylhexyl homoterephthalate, di-2-ethyloctylhomoterephthalate, di-Z-methyloctyl homoterephthalate, di- 3-ethyloctylhomoterephthalate, di-3-propyldecyl homoterephthalate,di-Z-methyl-fi-ethyloctyl homoterephthalate, di n decylhomoterephthalate, di 2 methyldecyl homoterephthalate, di-3-methyldecylhomoterephthalate, di-S-ethyldecyl homoterephthalate, di-n-undecylhomoterephthalate, di-2-propy1 undecyl homoterephthalate, di-n-tridecylhomoterephthalate, di-4-ethyl tridecyl homoterephthalate, di-S-methylhexadecyl homoterephthalate, di-S-hexadecyl homoterephthalate,di-n-heptadecyl homoterephthalate, di-3-butyl octadecylhomoterephthalate, di-n-eicosyl homoterephthalate, di-n-heneicosylhomoterephthalate, di-n-trieicosyl homoterephthalate, di-10- pentyltetraeicosyl homoterephthalate, and the like.

Typical examples of mixed esters of homoterephthalic acid are octylalpha-hexyl homoterephthalate (i.e., the hexyl ester of the carboxylicgroup is attached to the alpha-carbon atom which forms the methylenebridge which in turn is bonded to the ring whereas the octyl group isbonded to the other carboxyl group), 2-ethylhexyl alpha-octylhomoterephthalate, octyl alpha-decyl homoterephthalate, 3-ethyldecylalpha-octyl homoterephthalate, and the like.

Typical examples of alkoxyalkyl homoterephthalates are di-2-ethoxyethylhomoterephthalate, di-2-methoxyethyl homoterephthalate,d.i-4-methoxybutyl homoterephthalate, di-S-butoxyoctylhomoterephthalate, and the like.

The compounds of this invention are generally produced by esterificationof homoterephth'alic acid with an appropriate alcohol. This reaction mayor may not take place in the presence of a catalyst and usually at thereflux temperature of the system.

The catalysts generally used in the reaction of this type are acidcatalysts such as p-toluene sulfonic acid, anhydrous hydrogen chloride,sulfuric acid, and the like. These acid catalysts when employed can beused in an amount of from about 1 percent to 50 percent by weight basedon the acid being esterified. The preferred range, however, is fromabout 2 percent to about 5 percent based on the weight of said acid. Thetemperature at which the reaction is run is usually at the refluxtemperature of the system except when the boiling point of the alcoholis over about 180 C.

When such a high boiling alcohol is present, an azeotropic hydrocarbonsolvent would generally be employed to prevent undesirable sidereactions of the alcohol at the extremely high temperatures which wouldotherwise be required. Solvents generally employed are toluene, benzene,aromatic naphthas, and the like. The ratio of reactants used in thisesterification reaction ranges from 1.1:1 to 30:1 (mole ratio of alcoholto acid). The preferred ratio is 2:1 to 5:1 since this gives the bestyields with the least difficulty of product separation and isolation.The reaction time is usually from about 4 to about 18 hours.

Another process by which the compounds of this invention may be producedis by the ester interchange method comprising reacting a given ester ofhomoterephthalate acid with an alcohol containing the desired esterfunction. In this way the original ester groups are replaced by thedesired ester functions. In this method the reaction conditions areessentially as described above.

The methods by which the compounds of this invention are produced can befurther understood by the fol lowing examples. All quantities andpercentages are by weight unless otherwise designated.

EXAMPLE I Homoterephthalic acid (54 parts) was reacted with 117 parts ofn-oct-anol using 3 parts of p-toluene sulfonic acid as a catalyst with600 parts by volume of toluene as a solvent. The mixture was heated toreflux temperature and the water formed on esterification was removed asthe azeotrope with toluene. When no more water was removed (after 16hours of refluxing) the mass was cooled and washed with saturated brineto remove the catalyst. The mixture was then dried over anhydrous CaClThe mixture was then vacuum distilled. The fraction boiling from 213-219C. at 0.4 mm. mercury was collected and found to be di-n-octylhomoterephthalate, a colorless liquid (77 percent yield).

EXAMPLE II A round bottomed flask was charged with 112 parts of dimethylhomoterephthalate, 140 parts of purified 2- ethylhexanol, and 2.3 partsof p-toluene sulfonic acid monohydrate. The mixture was heated for 3hours and 4042 parts by volume of methanol were recovered through adistilling column attached to the flask. The residue in the flask wasdissolved in xylene, washed with NaOH and water, and dried by filtrationthrough anhydrous Na SO Distillation at 0.2 mm. Hg gave 120 parts byvolume (58.5 percent yield) of colorless liquid, boiling at 194195 C.,which was identified as di-2- ethylhexyl homoterephthalate.

EXAMPLE III Dimethyl homoterephthalate (21 parts), n-octadecanol (81parts) and p-toluene sulfonic acid (2 parts) were charged to a flaskprovided with distillation take off for removal of methanol and heatedto reflux. The product was taken up in toluene and washed with water toremove the catalyst and then dried over magnesium sulfate. It was thenvacuum distilled at 170 C. to remove the octadecanol, the productremaining in the pot. This was then dissolved in 400 parts by volume ofbenzene and passed through a silica gel column using benzene as wash.The product remaining on the column was washed off with methanol. Thiswas found by chemical analysis to be octadecanol. The ester wasrecovered from the benzene solution by distilling off the benzene. Thedioctadecyl homoterephthalate, a white solid melting at 56 C., wasthereupon recovered in 70 percent yield.

EXAMPLE IV Dimethyl homoterephthalate (21 parts), n-butyl alcoholparts), and p-toluene sulfonic acid (2 parts) were placed in a flaskprovided with Vigreux column and takeoff head and heated to the refluxtemperature of the system for a period of 5 hours. The reaction mass waswashed with water to remove the acid. The oily layer was then separatedand dried by the use of magnesium sulfate. This fraction was filteredand fractionated. The fraction boiling between 191 to 200 C. at 4 mm. Hgwas recovered and identified by chemical analysis as di-n-butylhomoterephthalate, a colorless liquid. The product was produced in 91.5percent yield.

EXAMPLE V Dimethyl homoterephthalate (2 parts), 2-butoxy ethanol (6parts), and 2 parts of p-toluene sulfonic acid are placed in a flaskfitted with a reflux condenser and heated for 6 hours at the refluxtemperature of the system. The. methanol is removed and the residue inthe flask is dissolved in xylene, washed with aqueous sodium hydroxide;and with water. The residue is dried by filtration through anhydrous NaSO Distillation at 0.5 mm. Hg gives a good yield of dibutoxyethylhomoterphthalate.

EXAMPLE VI Dimethyl homoterephthalate (23 parts), hexanol parts) and 2parts of p-toluene sulfonic acid are placed in a flask fitted with areflux condenser and heated for S hours at the reflux temperature of thesystem. The metha-- nol is removed and the residue in the flask isdissolved in xylene, washed with aqueous sodium hydroxide solu-- tionand then with water. The residue is dried by filt r a tion throughanhydrous Na SO Distillation at 0.4 mg. Hg gives a good yield of dihexylhomoterephthalate.

The methods of preparing these and the other esters of this inventionwill now be apparent to those skilled in the art.

This invention is predicated in part on the discovery that each alkyl oralkoxyalkyl group on the ester must have 4 or more carbon atoms. Forexample, this structure confers upon the present compounds thecharacteristics of an excellent plasticizer. On the other hand, wherealkyls or alkoxyalkyls have less than 4 carbons each, the compounds areWorthless as plasticizers. To illustrate, di-Z- ethylhexylhomoterphthalate, a compound of this invention, was tested and comparedwith dimethyl homoterephthalate for purposes of evaluation as aplasticizer. Di- Z-ethylhexyl homoterephthalate was found to haveexcellent properties whereas the dimethyl homoterephthalate was found tohave extremely poor properties, the test criteria used being weight lossduring milling, tensile modulus at 100 percent elongation, ultimatetensile strength utlimate elongation.

In particular, each of the esters was compounded with polyvinyl chlorideon a steam bath for 5 minutes until a mix approaching a dry blend wasobtained. The mix was then poured on an equal speed 2-roll mill andmilled at 310 F. for 7 minutes. Plasticized polyvinyl chloride sheetswere obtained and were tested under accelerated aging tests by weighingthe newly milled plastics and then immersing them in a Barnaby-Cheneyactivated carbon for 42 hours at 80 C. The plastic specimens were thenremoved from the activated carbon, reweighed and tested for tensilemodulus at 100 percent elongation and for ultimate tensile strength.Ultimate tensile strength is the force required to break the sample bystretching it and is measured in pounds per square inch. Tensile modulusat 100 percent elongation is the measure of force of pull at this degreeof extension. The tensile tests were conducted on an Instron machine,clamping distance 2 /2, machine speed 20 per minute, and gauge lengthof 1. The tests were performed at 73 F. at 50 percent relative humidity.The results of the tests are set out in Tables I and II. Table I showsthe averages of the 4 tests that were completed on each batch of theplasticized polyvinyl chloride.

6 The results of an additional series of tests are shown in Table II.

TABLE IL-EFFECT OF CHEMICAL STRUCTURE ON PLAS- TICIZER PERFO RMANCEDirnethyl Homoterephthalate 1 2 g. sheet dissolved in THF, PVCprecipitated with methanol filtered OE and dried in vacuum oven. Weightdifierence is plasticizer plus stabilizer.

P.h.r.=Parts per hundred parts (concentration).

As can be seen by the results in Table II, the dimethylhomoterephthalate does not have the permanence required for a goodplasticizer. For instance, parts of ester per 100 parts of polyvinylchloride were mixed and milled after which the amount of the plasticizerpresent in the resin was measured. There was found to be a loss of up to31.7 percent of the dimethyl homoterephthalate plasticizer during themilling process. However, when the di-2-ethylhexyl homoterephthalate wasadded to the polyvinyl chloride and milled and then the amount of theremaining 2ethylhexyl ester measured, there was found to be nodetectable loss during the milling process. In other words, this esterhad total permanence under the test conditions. The tensile modulus ofthe finished products was measured to determine the plasticizerefficiency. Plasticizer efiiciency can be defined as the amount ofplasticizer required to produce a standard flexibility (standard modulusat 100 percent elongation). Tensile modulus at 100 percent elongation,expressed in pounds per square inch, is a measure of the amount of forcerequired to stretch the sample plastic to 100 percent elongation. Asseen in Table II, 60 parts of dimethyl TABLE I.EI*FECT OF ACOELERATEDAGING ON TENSILE PROPERTIES 1 Parts or hundred parts of polyvinylchloride. 2 lmmei sed in Barnaby-Cheney activated carbon 42 hours at 80C.

the numb-er the better the plasticiZa-tion) for the di-2- ethylhexylhomoterephthalate system was only 12.2 percent. In sharp contrast, tothis, the net change of tensile modulus of the dimethylhomoterephthalate plastic was 59 percent.

It is also readily seen in Table I that the dimethyl homoterephthalateplastic had a 6.7 percent weight loss upon aging whereas thedi-2-ethylhexy1 homoterephthalate had only a 0.43 percent weight loss.

homoterephthalate per parts of the resin gave a plastic with a modulusof 1,715 pounds per square inch at 100 percent elongation whereas withonly 50 parts (per 100) of di-2-ethylhexyl homoterephthalate, theresultant resin had a modulus of 1,515 pounds per square inch at 100percent elongation. In other words, in this instance the larger thenumber, the less efficient the plasticizer. It is readily seen thereforethat it requires less di-2-ethylhexyl homoterephthalate to plasticizepolyvinyl chloride than it does when attempting to use dimethylhomoterephthalate. Furthermore, the ultimate elongation of the samplestested demonstrated that the di-2-ethylhexyl homoterephthalateplasticized polyvinyl chloride showed higher ultimate elongation thanthe dimethyl homoterephthalate plasticized polyvinyl chloride. (In thiscase, the higher the number the more flexible the plastic.)

Thus, it is readily seen that di-Z-ethylhexyl homoterephthalate is amuch superior plasticizer than is dimethyl homoterephthalate.

The value of the compounds of the present invention is even moredramatically illustrated by the tests conducted using di-n-octylhomoterephthalate as a plasticizer. For comparative purposes, companiontests were run using dioctyl phthalate, a widely-used commercialplasticizer. Tensile strength at 100 percent elongation, ultimatetensile and ultimate elongation of the test samples were determined inthe same manner as described above. Over and above this, standard ASTMlow temperature brittle tests were conducted on these plasticizedpolyvinyl chloride specimens. The results of the tests are presented inTable III.

TABLE IIL-EFFECT OF PLASTICIZER CONTENT ON PLAS- TIOIZED PVC PROPERTIES*Approx. standard modulus (1,500 p.s.i. at 100% elongation) plasticizercontent.

1 P.h.r. =Parts/100 resin.

2 Standard Test ASTM D412, 20/min., 73 F, 50% RH, average of 3specimens.

3 Standard Test ASTM D746-5l.

As can be readily observed by the results in Table III, di-n-octylhomoterephthalate, a compound of this invention, is a very superiorplasticizer. The tensile modulus at 100 percent elongation in Table IIIdemonstrates that the di-n-octyl homoterephthalate requires less forceto stretch it, thus it is more flexible (the lower the number the moreeflicient the plasticizer). As has been stated hereinbefore, plasticizerefliciency is measured by the amount of plasticizer required to producea standard flexibility. The ultimate elongation of the di-n-octylhomoterephthalate is also superior to the dioctyl phthalate (the higherthe number the more flexible the product, thus the better theplasticizer).

The brittle failure temperature was demonstrated by carrying out thetest according to ASTM D746-51. Samples were prepared by cutting A widestrips of the plastic to be tested. Several strips were clamped in aclamping device and immersed 3 minutes in a methanol Dry Ice mixture atthe temperature desired. The strips were then removed and subjectedimmediately to impact from a pendulum device. The temperature isprogressively lowered until a temperature is found at which 50 percentof the specimens break or crack when subjected to impact. Hence, thelower the temperature, the more efficient is the plasticizer. In fact,in actual practice it is desirable to have a brittle failure temperatureas low as 50 F. As has been pointed out in Table III, dioctyl phthalatehas a brittle temperature of 24 F. In sharp contrast to this poorresult, di-n-octyl homoterephthalate, a compound of this invention, canbe exposed to temperatures as low as 52 F. before 50 percent brittlefailure occurs.

In summary, therefore, the foregoing tests established that the presenceof esters of this invention in polyvinyl chloride gave a superiorbalance of tensile strength, elongation, low temperature flexibility,permanence, and low migration tendency.

Over and above these excellent features exhibited by the di-n-octylhomoterephthalate, the compound was also found to be a compatibleplasticizer for not only polyvinyl chloride, but for vinylchloride-vinyl acetate copolymer, polyvinyl butyral, celluloseacetate-cellulose butyrate, cellulose nitrate, ethyl cellulose,chlorinated rubber, and gum shellac. Hence, this invention extends tothe incorporation of plasticizing quantities of from about 10 to aboutweight percent of the compound of this invention in various plastics,such as those just described.

The plasticizing of various polymers such as polyvinyl chloride can alsobe accomplished by the use of mixed esters of homoterephthalic acid. Themixed esters such as butyl-a-Z-ethylhexyl homoterephthalate possess abalance of features such as compatibility, low volatility, lowtemperature flexibility, and the like. Accordingly, these mixed estersare oftentimes ideally suited for special applications where theseproperties are of utmost importance. Similarly mixtures of esters ofhomoterephthalic acid such as di-n-butyl homoterephthalate anddi-n-octyl homoterephalate; di-Z-ethoxyethyl homoterephthalate anddi-n-decyl homoterephthalate; and diisohexyl homoterephthtalate,di-3-methyldecyl homoterephthalate and di- 4-methoxybutylhomoterephthalate; and the like may be used to plasticize various resinssuch as polyvinyl chloride to impart to the end product such superiorproperties as flexibility, permanence, strength, and the like.

The compounds of this invention may also be used in conjunction withpreviously known plasticizers such as -di-n-octyl sebacate,di-Z-ethylhexyl sebacate, dibutyl sebacate, dibutyl adipate, tricresylphosphate, dibutyl phthalate, di-n-octyl phthalate, diisooctylphthalate, diamyl phthalate, octyl oleate, octyl stearate, triphenylphosphate, and the like. A particular advantage of these mixtures isthat in many cases they impart upon the resin a synergistic effectinsofar as plasticizing eifectiveness is concerned. Moreover, a numberof these mixtures results in markedly improved resin products such asresin products possessing improved clarity (low fish eye count), goodheat stability, low migration, low volatility, superior strength, andthe like. Normally when such mixtures are prepared the proportion ofheretofore known plasticizer to a compound of this invention will rangefrom about 10 to about weight percent. The resulting mixture ofplasticizers can be used to plasticize polyvinyl chloride or othersimilar resins in an amount ranging from about 10 to about 80 Weightpercent (plasticizer to resin). This permits one to create a tailor-madeplasticizer designed specifically for the end use of the plasticproduct.

The alkyl and alkoxyalkyl esters of homoterephthalic acid have alsoproved to be excellent when used as synthetic lubricants. For example,these compounds have superior thermal stability up to 600 F. As a matterof fact, tests have shown that no significant oxidative deterioration ofthe lubricant occurred even under these high temperature conditions. Forexample, when di-2- ethylhexyl homoterephthalate, a particularlypreferred compound of this invention, was tested as a syntheticlubricant and compared to di-2-ethylhexyl sebacate, a standardcommercial synthetic lubricant, the homoterephthalate ester was found tohave superior properties. One particular comparative test run on thesetwo compounds was the Panel-Coker test for high temperature evaluationand oxidation stability. This test is described in the AeronauticalStandards group of the Departments of Navy and Air Force SpecificationsMIL-L7808C dated November 2, 1955. The test was conducted at 600 F. fora period of 4 /2 hours. At the end of this time the test panel incontact with the di-Z-ethylhexyl homoterephthalate had shown a Weightgain of only 11 milligrams as compared to the weight gains of 72 and 66milligrams for the di-2-ethylhexyl sebacate test panels. Furthermore,upon examining the test oils themselves upon completion of the tests, itwas found that the di-Z-ethylhexyl sebacate had undergone deteriorationsince it contained a dark brown gummy residue. However, thedi-2-ethylhexyl homoterephthalate was still a water clear liquidcontaining essentially no residue. Moreover, its lubricating propertieswere unimpaired. This dramatically points out that the di-Z-ethylhexylhomoterephthalate, a compound of this invention, exhibits far superiorthermal stability and oxidative stability properties than does thecommercial sebacate ester. These superior properties render thehomoterephthalate ester even more useful as a synthetic lubricant thanthe sebacate ester.

Besides obtaining very effective lubrication by using the esters ofhomoterephthalic acid per se to lubricate relatively-moving, contactingmetallic surfaces, excellent lubrication is also achieved when theseesters are used in conjunction with known lubricants. Thus, thesynthetic lubricants of this invention comprise the above definedesters, which may be used in combination with one or more standardlubricants, such as mineral lubricating oils, synthetic esterlubricants, silicones, chlordiphenyl oils, and the like. Typicalexamples of synthetic ester lubricants with which the compounds of thisinvention can be successfully used are diethyl oxalate, di-sec-butylmalonate, di- (2-hexyl succinate, di- (isoheptyl pimelate,di-(3-decyl)suberate, di-sec-amyl glutarate, di-(isobutyl) glutarate,di-(Z-ethylbutyl)glutarate, di-sec-amyl adipate,di-(3-methylbutyl)adipate, diethyl adipate, di-(4-propylcyclohexyl)adipate, di-2ethylhexyl adipate, di-sec-amyl azelate,di-(isobutyl)azelate, di-(2-ethylbutyl)azelate, di- (ethylhexyl)azelate,di-sec-amyl sebacate, di-sec-butyl sebacate, di (2 ethylhexyl)sebacate,bis (1 methyl- 1-cyclohexyl)sebacate, the glutarates, adipates, azelatesand sebacates of branched chain secondary alcohols such as undecanol,tetradecanol, etc.; the butyl, penty-l, hexyl, heptyl, octyl, nonyl,decyl, undecyl, and dodecyl esters of polyol such as pentaerythritol,trimethylol propane, trimethylol ethane, etc.; and other esters of thetype described in the literature as useful for synthetic lubricants.Generally speaking, the compounds of this invention will be present inthe finished lubricant to a concentration ranging from about 5 to about95 percent by weight, the balance being one or more previously-knownlubricants.

As further examples of this invention use is made of the standard Lausonengine test. According to this test, a standard spark-ignition internalcombustion engine is operated. for 25 hours using a standard fuel. Theengine is examined before and after the test and merit ratings as tovarnish formation are given according to the test standards. The ratingscale involves numbers from 0 to 10, 0 being a perfect rating. Thus,this test very effectively evaluates the usefulness of the enginelubricant subjected to the test. As a base line, the engine is operatedusing an oily-refined mineral lubricating oil having a viscosity of 60Saybolt Universal seconds at 210 F. as a lubricant. The test is thenrepeated a number of times, in each test using, being made of one of thefollow ing esters of homoterephthalic acid as a lubricant-di-noctylhomoterephthalate; di-Z-ethylhexyl homoterephthalate; di-butoxy ethylhomoterephthalate; diisohexyl homoterephthalate; di-n-hexylhomoterephthalate; di-Z- methylhexyl homoterephthalate; di-3-ethylhexylhomoterephthalate; di-2-ethyloctyl homoterephthalate; di-2- methyloctylhomoterephthalate; di-n-decyl homoterephthalate; di-2-methyldecylhomoterephthalate; di-2-ethoxyethyl homoterephthalate;di-Z-methoxypentyl homoterephthalate; di-4-methoxybutylhomoterephthalate; and octyl-a-hexyl homoterephthalate. In eachinstance, the use of these esters results in superior merit ratings ascompared with the base line rating.

Typical lubricant formulations provided by this invention are given inthe following examples in which all pep centages are by weight.

EXAMPLE VII A lubricant is formulated to contain percent of di- 10(2ethylhexyl)sebacate and 90 percent di-Z-ethylhexyl homoterephthalate.

EXAMPLE VIII A lubricant is formed from 15 percent of di-n-octylsebacate, 5 percent tricresyl phosphate, 1 percent phenothiazine, with79 percent di-n-hexyl homoterephthalate.

EXAMPLE IX A lubricant is formulated to contain 3 percent tricresylphosphate, 7 percent dioctyl phthalate, 10 percent highly refinedmineral lubricating oil having a viscosity of 60 Saybolt Universalseconds at 210 F. and 80 percent of di-n-octyl homoterephthalate.

EXAMPLE X A lubricant is made from percent highly refined mineral oilhaving a viscosity of Saybolt Universal seconds at 210 F. and 50 percentdibutoxy ethyl homoterephthalate.

EXAMPLE XI A lubricant is made from 30 percent tricresyl phosphate, 30percent dibutoxy ethyl homoterephthalate and 40 percent di-Z-ethylhexylhomoterephthalate.

EXAMPLE XII A lubricant is formulated to contain 20 percentpentaerythritol and percent diisohexyl homoterephthalate.

When the esters of homoterephthalic acid are used as lubricants,effective use can be made of other additives which are known to the art,such as other inhibitors, detergents-depressants, pour pointdepressants, viscosity index improvers, anti-foam agents, rustinhibitors, oiliness of film strength agents, dyes and the like. Of theinhibitors which can be effectively used with the present additivecombinations are sulfurized sperm oil, sulfurized terpenes, sulfurizedparaflin wax olefins, aromatic sulfides, alkyl phenol sulfides,lecithin, neutralized dithiophosphates, phosphorous pentasulfide-terpenereaction products, diphenyl amine, phenyl naphthyl amine, 4,4-methylenebis(2,6 di tert butylphenol), N (3,5ditert-butyl-4-hydroxybenzyl), N,N-dimethyl amine, and the like. Typicalof the detergent additives that can be used in the compositions of thisinvention are metallic soaps of high molecular weight acids such asaluminum naphthenates, calcium phenol stearates, calcium alkylsalicylates, alkaline earth metal petroleum sulfonates, alkaline earthmetal alkyl phenol sulfides (barium ethyl phenol sulfide, calcium octylphenol, phenol disulfide, etc.), metal salts of wax substituted phenolderivatives, and the like. Of the viscosity index improvers and pourpoint depressants effective use can be made of polymers of the esters ofmethacrylic acids, higher fatty alcohols and the corresponding polymericesters of acrylic acids and higher fatty alcohols. Other very usefulviscosity index improvers are the polyisobutylenes and polyvinyl ethers.These and other additives which can be employed in the compositions ofthis invention and. the concentrations and proportions thereof will nowbe well known to those skilled in the art.

The compounds of this invention can also be put tomany other uses suchas insect repellants; alcohol denaturants; ingredients in such materialsas emulsion paints, smokeless gun powder; and the like.

Having thus described the compositions of matter and their uses it isnot intended that this invention be limited except as set forth in thefollowing claims.

What is claimed is:

1. As a new composition of matter, polyvinyl chloride containing as aplasticizer therefor a dialkoxyalkyl homoterephthalate in which eachalkoxyalkyl group contains from 4 to about 24 carbon atoms.

3,224,995 11 12 2. The composition of claim 1 wherein said homo-References Cited by the Examiner terephthalate is dibutoxyethylhomoterephthalate. UNITED STATES PATENTS 3. Polyvinyl chloridecontaining from about 10 to about 80 weight percent of a dialkoxyalkylhomotereph- 2,339,373 1/1944 BYUFOH 260*475 thalate in which eachalkoxyalkyl group contains from 4 5 216281207 2/1953 Smlth et a1 260 475to about 24 carbon atoms. 2,642,457 6/1953 Emerson et a1. 26()-475 4.The composition of claim 3 wherein said homoterephthalate isdibutoxyethyl homoterephthalate. MORRIS LIEBMAN Prlmary Exammer'

1. AS A NEW COMPOSITONS OF MATTER, POLYVINYL CHLORIDE CONTAINING AS A PLASTICIZER THEREFOR A DIALKOXYALKYL HOMOTEREPHTHALATE IN WHICH EACH ALKOXYALKYL GROUP CONTAINS FROM 4 TO ABOUT 24 CARBON ATOMS. 